springboot 使用freemarker自定义标签

1、pom依赖引入

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

2、application配置

#服务启动端口
server.port=8080

## Freemarker 配置
spring.freemarker.cache=false
spring.freemarker.charset=UTF-8
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=true
spring.freemarker.expose-session-attributes=true
spring.freemarker.request-context-attribute=request
spring.freemarker.suffix=.ftl

3、实现TemplateDirectiveModel

package com.example.springbootfreemarker.tags.directive;

import freemarker.core.Environment;
import freemarker.template.*;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@Component
public class MyTagDirective implements TemplateDirectiveModel{
    @Override
    public void execute(Environment environment, Map map, TemplateModel[] templateModels, TemplateDirectiveBody templateDirectiveBody) throws TemplateException, IOException {
        Integer tagId = -1;
        String tagName = "";

        //自己的逻辑 todo
        Map<String, Object> result = new HashMap<String, Object>(2);
        if (map.containsKey("tagId")){
            tagId = Integer.parseInt(map.get("tagId").toString());
        }

        if (map.containsKey("tagName")){
            tagName = (String)map.get("tagName").toString();
        }

        result.put("tagId", tagId);
        result.put("tagName", tagName);

        DefaultObjectWrapperBuilder builder = new DefaultObjectWrapperBuilder(Configuration.VERSION_2_3_25);
　　　　　//此处的myTag就是返回给前端的数据
        environment.setVariable("myTag", builder.build().wrap(result));
        templateDirectiveBody.render(environment.getOut());
    }
}

前端文件：

<!DOCTYPE html>

<html lang="en">

<body>
    hello, ${name}, let's go!
    <@myTag tagId = 1 tagName = "mytag">
        <#if myTag??>
            <p>${myTag.tagId},${myTag.tagName}</p>
        </#if>
    </@myTag>
</body>

</html>

用法：跟自定义macro用法一样，直接使用 <@xx></@xx> 来使用即可，值就直接在myTag 标签里传就可以了

流程：当访问前端页面时，会将自定义的标签及其值传到后台MyTagDirective拦截处理并返回结果给前端渲染使用，<#if myTag??>为freemarker语法，可参照freemarker语法

springboot 使用freemarker自定义标签

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